Polyaniline prepared in solutions of phosphoric acid: Powders, thin films, and colloidal dispersions

Thin PANI films were produced in situ on glass surfaces immersed in the reaction mixture during the polymerization of aniline. Optical absorption has been used to assess their thickness, 70-140 nm, which was found to be virtually independent of the acid concentration. The film conductivity was comparable with the conductivity of the PANI powders produced at the same time. Colloidal dispersions were obtained when the reaction mixture contained poly(N-vinylpyrrolidone). The particle size, 200-260 nm, and polydispersity, determined by dynamic light scattering, were virtually independent of the concentration of phosphoric acid. The films produced on glass during the dispersion polymerization of aniline were thinner, 20-90 nm, compared with those grown in the precipitation polymerization.